Opponents of the Michigan gay marriage ban walk in front of the federal courthouse in Detroit before the start of a case challenging it, Tuesday morning, Feb. 25, 2014.

(Katie Bailey | MLive.com)

LANSING, MI -- A majority of Michigan residents support gay marriage a decade after voters approved a constitutional ban that is now on trial, according to the results of a new statewide survey, and those supporters appear to be growing more confident in their beliefs.

Results from Michigan State University's latest State of the State Survey, released Friday, suggest that 54 percent of residents favor "the right of gay and lesbian couples to be legally married," while 36 percent are opposed.

The survey of 1,008 residents, conducted via landline and cellphone over an eight-week period ending February 10, has a margin of error of 3.1 percent. Ten percent of respondents were undecided.

The new numbers are similar to State of the State findings from 2012, when 55 percent of respondents said they supported gay marriage and 39 percent opposed it, but they are significantly higher than in 2010, when a majority of respondents still said they opposed same-sex marriage.

While the overall numbers have not changed much in two years, more residents now say they "strongly" support -- as opposed to "somewhat" support -- gay marriage, according to MSU Economics Professor Charles Ballard.

"The support has sort of coalesced, or strengthened," said Ballard, who directs the survey. "It's the first time we've seen numbers this large. More than 35 percent say not just that they favor gay marriage, but that they strongly favor it."

Back in 2004, more than 58 percent of Michigan voters approved a constitutional amendment defining marriage as between one man and one woman. Backers say that gay marriage polls can be misleading because some respondents are uncomfortable expressing opinions they might act on in the voting booth.

Michigan's same-sex marriage ban is now on trial before a federal judge in Detroit, who is considering a challenge filed on behalf of two Hazel Park nurses alleging discrimination and seeking joint custody of their adopted children. They are not allowed to marry, but Michigan law only allows joint adoption by married couples.

The MSU survey did not make specific reference to joint adoption or the rights of heterosexual couples, but it did ask residents whether they favor allowing gay and lesbians to adopt children. Roughly 59 percent of respondents offered support, while 33 percent expressed opposition.

The survey showed a significant shift in gay marriage attitudes amongst black residents, with 47 percent of respondents offering support, up from just 31 percent in 2012.

Residents with some college education were more likely to favor same-sex marriage, with 56 percent expressing support compared to 49 percent of residents who had never been to college.

Gay marriage was supported by 86 percent of respondents who said they had no religious preference, 55 percent who identified themselves as Catholic and 42 percent of protestants.

There was also a notable difference amongst age groups, with 68 percent of respondents under the age of 30 expressing support for same-sex marriage, compared to 46.9 percent of those 65 and older.

"I'd say that there is definitely a generational component to it," said Ballard.

Jonathan Oosting is a Capitol reporter for MLive Media Group. Email him, find him on Google+ or follow him on Twitter.